The aim of this experimental study is to investigate the interaction between turbulent flow and a gravel-bed that mimics the actual roughness structures of a natural bed and its implication on sediment transport. In particular, the response of the Reynolds stresses and the role of intermittency to the bed roughness is the primary focus of the current study. To this end, the flow field, measured with an Acoustic–Doppler Velocimeter (ADV), is thoroughly examined, considering the conditional Reynolds shear stresses and the high-order structure functions of velocity. The study results show that the features and the roughness structure of the water-worked gravel-bed (WWGB) have a strong impact on bursting events. The reason for this is attributed to the flow layer above the crest in the WWGBs being primarily affected by sweep events rather than ejection events, although the latter events are prevalent in this flow layer in an immobile, man-made, gravel-bed. These coherent structures, which are primarily responsible for sediment transport, also are the key cause of the presence of an intermittency excess that breaks the Kolmogorov self-similarity hypothesis, leading to multi-fractal behavior of the velocity structure functions.

本实验研究的目的是研究湍流和砾石床之间的相互作用，该砾石床模拟天然床的实际粗糙度结构及其对沉积物输送的影响。特别是，雷诺应力的响应和间歇性对床层粗糙度的作用是当前研究的主要焦点。为此，考虑到条件雷诺剪切应力和速度的高阶结构函数，对使用声-多普勒测速仪 (ADV) 测量的流场进行了彻底检查。研究结果表明，水处理砾石层（WWGB）的特征和粗糙度结构对爆裂事件有很强的影响。造成这种情况的原因是 WWGB 顶部上方的流动层主要受扫掠事件而不是喷射事件的影响，尽管后者在该流动层中普遍存在于不动的人造砾石层中。这些主要负责沉积物输送的连贯结构也是出现间歇性过剩的关键原因，这打破了 Kolmogorov 自相似假设，导致速度结构函数的多重分形行为。